Download Snack Tectonics

Snack Tectonics Lab
Purpose:
The purpose of the lab is to visualize the interactions that occur at plate boundaries.
Procedure Materials:
1. 1 Fruit by the Foot roll
2. 2 Graham crackers
3. Large dollop of frosting
4. Water
5. Plastic knife
6. Wax paper
7. Plastic cup
Directions:
Before jumping into Part I below, read Background information provided. Highlight key concepts and
important points to remember.
*ALL MEMBERS OF THE LAB GROUP, Thoroughly WASH AND DRY HANDS!
*MAKE SURE YOUR LAB STATION IS CLEAN AND DRY
*DO NOT EAT ANY MATERIALS UNTIL YOU ARE COMPLETELY FINISHED WITH THE LAB!
Background Information
The main force that shapes our planet's surface over large amounts of geologic time is the
movement of Earth's outer layer through the process of plate tectonics. The rigid outer layer of the
Earth, called the lithosphere, is made of plates that fit together like a jigsaw puzzle. These plates
are made of rock, but the rock is, in general, lightweight compared with the denser, fluid layer
underneath. This allows the plates to "float" on top of the denser material. The fluid dense
material is called asthenosphere and in this activity the frosting represents it. However, plates
are not all the same. Plates made of continental crust are thicker but less dense than plates made
of oceanic crust, which are denser but thinner. In this activity, oceanic crust is represented by
fruit roll ups and continental crust is represented by graham crackers. Movements deep within the
Earth, which carry heat from the hot interior to the cooler surface, cause the plates (crust) to move
very slowly on the surface, about 2 inches per year on average. There are several different
hypotheses to explain exactly how these motions allow plates to move. Interesting things happen
at the edges of plates. At divergent plate boundaries, rift valleys and spreading ridges form as
plates pull away from each other. At convergent plate boundaries, where plates are coming
together, subduction zones form when an oceanic plate and a continental plate collide and
mountains build when two continental plates collide. Large transform faults form when plates
slide past each other making the Earth tremble with earthquakes.
Background Information Questions
Snack Tectonics Lab
1. If Earth’s plate interaction is modeled, what types of plate boundaries can be visualized?
2. Which Earth layer will the graham cracker represent?
3. Which Earth layer will the fruit roll up represent?
4. Which Earth layer will the frosting represent?
Lab Procedure:
Part I: Divergent Plate Boundary
1. Place a large dollop of frosting on the wax paper. This will represent the fluid, middle mantle or
asthenosphere. Notice that it is not fluid like water, but is thick and sticky. However, the
asthenosphere can still move or flow.
2. Spread the asthenosphere (frosting) to an approximate thickness of 0.5 cm with the plastic knife.
3. Place the two oceanic plates (Fruit by the Foot) on the asthenosphere (frosting) so that the long edges
are touching.
4. Gently press down along the entire length of the edges that are touching (to stimulate the density of
the plates) and spread the plates about 0.5 cm apart. (Continue pushing down slightly as you spread
the plates apart.)
5. In “observations” draw a side view of what you see happening to oceanic plates and asthenosphere.
(This is what it would look like if you brought your eyes down to the level of the plates and looked at
the ends of both plates.)
6. In “observations” draw a top view of what you see happening. (This is what it would look like if you
were in an airplane flying over the top and looking down.)
7. Remove one of the oceanic plates and set it aside to use later. DO NOT EAT IT!
Part II: Convergent Plate Boundaries
Continental-Oceanic Plate Boundary
8. Smooth out the asthenosphere (frosting.)
9. Gently place one of the continental plates (graham cracker) on the asthenosphere so that it is
touching the longer edge of the oceanic plate.
10. Converge (push) the two plates together by pushing the continental plate from the back but do not
push down to simulate that continental plates are not very dense.
11. Push down on the entire length of the oceanic plate that is touching the continental plate.
12. Draw a side view of what you see happening in your observations.
13. Draw a top view of what you see happening.
14. Remove the oceanic plate and set it aside to use later. DO NOT EAT!
Continental-Continental Convergent Plate Boundary
15. Smooth out the asthenosphere (frosting.)
Snack Tectonics Lab
16. Fill the plastic cup with water. Submerge 1 cm of each of the continental plates (graham crackers) for
1-2 seconds. BE CAREFUL. If you leave the plates in the water too long, this part will not work.
17. Gently place the continental plates on the asthenosphere so that the entire wet edges are touching.
18. Without pushing down, slowly push the plates together from the back.
19. Draw a side view of what you see happening.
20. Draw a top view of what you see happening.
21. Remove the oceanic plate and set aside for later on a paper towel. DO NOT EAT THEM!
Make sure that the edges opposite the wet edges stay dry!
Oceanic-Oceanic Convergent Plate Boundary
22. Smooth out the asthenosphere (frosting.)
23. Place both pieces of oceanic crust on the asthenosphere so that he long edges are touching.
24. Gently press down along the entire edges that are touching and push the plates together.
Continue pushing down slightly as you push the plates together.
25. (Remember, you are trying to show how both plates will sink into the mantle.)
26. Draw a side view of what you see happening.
27. Draw a top view of what you see happening.
28. Set the two oceanic plates aside for later. DO NOT EAT THEM!
Part lll: Transform Plate Boundary
29. Smooth out the asthenosphere (frosting.)
30. Gently place the two pieces of continental crust on the asthenosphere so that the dry edges are
touching.
31. Hold the two continental plates from the back and very gently push them together as you slide one
plate towards you and one plate away from you.
32. Draw a side view of what you see happening.
33. Draw a top view of what you see happening.
34. You are now done with the activity and may eat any of the food you wish.
35. Clean up your lab station according to your teacher’s instructions.
Observations
Complete a drawing as described in the Sequence of Steps for each plate boundary. Include arrows to show the
direction the plates are moving.
PART l – DIVERGENT PLATE BOUNDARY
SIDE VIEW
TOP VIEW
Snack Tectonics Lab
PART ll – CONVERGENT PLATE BOUNDARY
1 – continental-oceanic convergent plate boundary
SIDE VIEW
TOP VIEW
2 – continental-continental convergent plate boundary
SIDE VIEW
TOP VIEW
3 – oceanic–oceanic convergent plate boundary
SIDE VIEW
TOP VIEW
PART lll – TRANSFORM PLATE BOUNDARY
SIDE VIEW
TOP VIEW
Analysis (Answer with complete sentences, using actual data and background reading.)
1. When plates move, which type will float higher on the asthenosphere? Explain.
2. Why is it important to know what types of plates are interacting at convergent plate boundaries, but
not divergent or transform? Explain.
Snack Tectonics Lab
3. Diagram a picture showing the direction of the plate movement and convection in the atmosphere
for a divergent plate boundary. Next to the drawing explain with words, why the plates diverge.
4. Diagram a picture showing the direction of plate movement and convection cell in the asthenosphere
for a convergent plate boundary. (This can be a simple picture and does not need to represent a
specific type of convergent plate boundary.) Next to the diagram explain with words, why plates
converge.
5. Diagram a picture showing the direction of plate movement at a transform plate boundary. (Do not
show the convection in the asthenosphere.)
6. How has the plate movement throughout history created natural resources, which help agricultural
production, as well as natural resources, which hinder agricultural production? Provide at least two
examples for each.